The arXiv preprint server has become central to the working lives of most physicists: 'checking the arXiv' is the starting point of many a daily routine. Founded by Paul Ginsparg, the arXiv has expanded to include not only physics — astrophysics, condensed matter, and high-energy physics being heavily represented — but also mathematics, computer science, quantitative biology and even quantitative finance. The arXiv now hosts nearly 600,000 preprints from 101,000 registered submitters in 200 countries, and serves more than 2.5 million article downloads every month to 400,000 users.

The statistics are remarkable. And it is also remarkable that, having initially been hosted at the Los Alamos National Laboratory, the server has in recent years been funded and managed by a single institute, Cornell University. Now the operating costs of the ever-growing arXiv match the entire Cornell library budget for physics and astronomy, and the university has made a plea for help in funding it.

As a short-term solution, Cornell is approaching the top 200 user-institutions of the arXiv — who account for 75% of institutional downloads — for a financial contribution to the maintenance of the arXiv. It is heartening that help has already been promised from several large universities and laboratories, but wider support is still being sought. For the longer term, Cornell will assess, with those who come forward to support the arXiv, what the options are in developing a sustainable model for the future.

Secure, ongoing funding of the preprint server is vital, and surely deserves at least national endorsement from US funding bodies, if not some international arrangement. The fast communication of results — data or theory — between experts that the arXiv facilitates is a boon to physics, and one well recognized by the Nature Publishing Group: any submission to Nature Physics or its sister journals may be posted, in that original submitted form, on the preprint server (although we do ask that the final, revised and accepted version is not posted until six months after publication in the journal; the published version, in the Nature Physics layout, may not be posted).

It's up to physicists now to sustain their arXiv, encouraging their institutions' libraries in particular to engage in its development. More information is available at http://arxiv.org/help/support; and comments and suggestions may be sent to support@arxiv.org.